Use @Nullable Void in TaskCallback#from

See gh-36208

spring-core/src/main/java/org/springframework/core/retry/support/RetryTask.java

@@ -196,8 +196,9 @@ public class RetryTask<V extends @Nullable Object, E extends Exception> implemen
 	 * @param retryTemplate the retry delegate to use (typically a {@link RetryTemplate}
 	 * but declaring the {@link RetryOperations} interface for flexibility)
 	 */
+	@SuppressWarnings("NullAway") // https://github.com/uber/NullAway/issues/1451
 	public static Runnable wrap(Runnable task, RetryOperations retryTemplate) {
-		RetryTask<Void, RuntimeException> rt = new RetryTask<>(TaskCallback.from(task), retryTemplate) {
+		RetryTask<@Nullable Void, RuntimeException> rt = new RetryTask<>(TaskCallback.from(task), retryTemplate) {
 			@Override
 			public String getName() {
 				return task.getClass().getName();

spring-core/src/main/java/org/springframework/core/task/TaskCallback.java

@@ -55,8 +55,7 @@ public interface TaskCallback<V extends @Nullable Object, E extends Exception> e
 	 * Derive a {@link TaskCallback} from the given {@link Runnable}.
 	 * @since 7.0.4
 	 */
-	@SuppressWarnings("NullAway")
-	static TaskCallback<Void, RuntimeException> from(Runnable task) {
+	static TaskCallback<@Nullable Void, RuntimeException> from(Runnable task) {
 		return () -> {
 			task.run();
 			return null;